pdfjs-dist
Version:
Generic build of Mozilla's PDF.js library.
330 lines (329 loc) • 11 kB
JavaScript
/**
* @licstart The following is the entire license notice for the
* JavaScript code in this page
*
* Copyright 2022 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @licend The above is the entire license notice for the
* JavaScript code in this page
*/
"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.TextLayerRenderTask = void 0;
exports.renderTextLayer = renderTextLayer;
var _util = require("../shared/util.js");
var _display_utils = require("./display_utils.js");
const MAX_TEXT_DIVS_TO_RENDER = 100000;
const DEFAULT_FONT_SIZE = 30;
const DEFAULT_FONT_ASCENT = 0.8;
const ascentCache = new Map();
function getAscent(fontFamily, ctx) {
const cachedAscent = ascentCache.get(fontFamily);
if (cachedAscent) {
return cachedAscent;
}
ctx.save();
ctx.font = `${DEFAULT_FONT_SIZE}px ${fontFamily}`;
const metrics = ctx.measureText("");
let ascent = metrics.fontBoundingBoxAscent;
let descent = Math.abs(metrics.fontBoundingBoxDescent);
if (ascent) {
ctx.restore();
const ratio = ascent / (ascent + descent);
ascentCache.set(fontFamily, ratio);
return ratio;
}
ctx.strokeStyle = "red";
ctx.clearRect(0, 0, DEFAULT_FONT_SIZE, DEFAULT_FONT_SIZE);
ctx.strokeText("g", 0, 0);
let pixels = ctx.getImageData(0, 0, DEFAULT_FONT_SIZE, DEFAULT_FONT_SIZE).data;
descent = 0;
for (let i = pixels.length - 1 - 3; i >= 0; i -= 4) {
if (pixels[i] > 0) {
descent = Math.ceil(i / 4 / DEFAULT_FONT_SIZE);
break;
}
}
ctx.clearRect(0, 0, DEFAULT_FONT_SIZE, DEFAULT_FONT_SIZE);
ctx.strokeText("A", 0, DEFAULT_FONT_SIZE);
pixels = ctx.getImageData(0, 0, DEFAULT_FONT_SIZE, DEFAULT_FONT_SIZE).data;
ascent = 0;
for (let i = 0, ii = pixels.length; i < ii; i += 4) {
if (pixels[i] > 0) {
ascent = DEFAULT_FONT_SIZE - Math.floor(i / 4 / DEFAULT_FONT_SIZE);
break;
}
}
ctx.restore();
if (ascent) {
const ratio = ascent / (ascent + descent);
ascentCache.set(fontFamily, ratio);
return ratio;
}
ascentCache.set(fontFamily, DEFAULT_FONT_ASCENT);
return DEFAULT_FONT_ASCENT;
}
function appendText(task, geom, styles, ctx) {
const textDiv = document.createElement("span");
const textDivProperties = {
angle: 0,
canvasWidth: 0,
hasText: geom.str !== "",
hasEOL: geom.hasEOL,
fontSize: 0
};
task._textDivs.push(textDiv);
const tx = _util.Util.transform(task._viewport.transform, geom.transform);
let angle = Math.atan2(tx[1], tx[0]);
const style = styles[geom.fontName];
if (style.vertical) {
angle += Math.PI / 2;
}
const fontHeight = Math.hypot(tx[2], tx[3]);
const fontAscent = fontHeight * getAscent(style.fontFamily, ctx);
let left, top;
if (angle === 0) {
left = tx[4];
top = tx[5] - fontAscent;
} else {
left = tx[4] + fontAscent * Math.sin(angle);
top = tx[5] - fontAscent * Math.cos(angle);
}
textDiv.style.left = `${left}px`;
textDiv.style.top = `${top}px`;
textDiv.style.fontSize = `${fontHeight}px`;
textDiv.style.fontFamily = style.fontFamily;
textDivProperties.fontSize = fontHeight;
textDiv.setAttribute("role", "presentation");
textDiv.textContent = geom.str;
textDiv.dir = geom.dir;
if (task._fontInspectorEnabled) {
textDiv.dataset.fontName = geom.fontName;
}
if (angle !== 0) {
textDivProperties.angle = angle * (180 / Math.PI);
}
let shouldScaleText = false;
if (geom.str.length > 1) {
shouldScaleText = true;
} else if (geom.str !== " " && geom.transform[0] !== geom.transform[3]) {
const absScaleX = Math.abs(geom.transform[0]),
absScaleY = Math.abs(geom.transform[3]);
if (absScaleX !== absScaleY && Math.max(absScaleX, absScaleY) / Math.min(absScaleX, absScaleY) > 1.5) {
shouldScaleText = true;
}
}
if (shouldScaleText) {
if (style.vertical) {
textDivProperties.canvasWidth = geom.height * task._viewport.scale;
} else {
textDivProperties.canvasWidth = geom.width * task._viewport.scale;
}
}
task._textDivProperties.set(textDiv, textDivProperties);
if (task._textContentStream) {
task._layoutText(textDiv);
}
}
function render(task) {
if (task._canceled) {
return;
}
const textDivs = task._textDivs;
const capability = task._capability;
const textDivsLength = textDivs.length;
if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
task._renderingDone = true;
capability.resolve();
return;
}
if (!task._textContentStream) {
for (const textDiv of textDivs) {
task._layoutText(textDiv);
}
}
task._renderingDone = true;
capability.resolve();
}
class TextLayerRenderTask {
constructor({
textContent,
textContentStream,
container,
viewport,
textDivs,
textContentItemsStr
}) {
this._textContent = textContent;
this._textContentStream = textContentStream;
this._container = container;
this._document = container.ownerDocument;
this._viewport = viewport;
this._textDivs = textDivs || [];
this._textContentItemsStr = textContentItemsStr || [];
this._fontInspectorEnabled = !!globalThis.FontInspector?.enabled;
this._reader = null;
this._layoutTextLastFontSize = null;
this._layoutTextLastFontFamily = null;
this._layoutTextCtx = null;
this._textDivProperties = new WeakMap();
this._renderingDone = false;
this._canceled = false;
this._capability = (0, _util.createPromiseCapability)();
this._renderTimer = null;
this._devicePixelRatio = globalThis.devicePixelRatio || 1;
this._capability.promise.finally(() => {
this._textDivProperties = null;
if (this._layoutTextCtx) {
this._layoutTextCtx.canvas.width = 0;
this._layoutTextCtx.canvas.height = 0;
this._layoutTextCtx = null;
}
}).catch(() => {});
}
get promise() {
return this._capability.promise;
}
cancel() {
this._canceled = true;
if (this._reader) {
this._reader.cancel(new _util.AbortException("TextLayer task cancelled.")).catch(() => {});
this._reader = null;
}
if (this._renderTimer !== null) {
clearTimeout(this._renderTimer);
this._renderTimer = null;
}
this._capability.reject(new Error("TextLayer task cancelled."));
}
_processItems(items, styleCache) {
for (const item of items) {
if (item.str === undefined) {
if (item.type === "beginMarkedContentProps" || item.type === "beginMarkedContent") {
const parent = this._container;
this._container = document.createElement("span");
this._container.classList.add("markedContent");
if (item.id !== null) {
this._container.setAttribute("id", `${item.id}`);
}
parent.append(this._container);
} else if (item.type === "endMarkedContent") {
this._container = this._container.parentNode;
}
continue;
}
this._textContentItemsStr.push(item.str);
appendText(this, item, styleCache, this._layoutTextCtx);
}
}
_layoutText(textDiv) {
const textDivProperties = this._textDivProperties.get(textDiv);
let transform = "";
if (textDivProperties.canvasWidth !== 0 && textDivProperties.hasText) {
const {
fontFamily
} = textDiv.style;
const {
fontSize
} = textDivProperties;
if (fontSize !== this._layoutTextLastFontSize || fontFamily !== this._layoutTextLastFontFamily) {
this._layoutTextCtx.font = `${fontSize * this._devicePixelRatio}px ${fontFamily}`;
this._layoutTextLastFontSize = fontSize;
this._layoutTextLastFontFamily = fontFamily;
}
const {
width
} = this._layoutTextCtx.measureText(textDiv.textContent);
if (width > 0) {
transform = `scaleX(${this._devicePixelRatio * textDivProperties.canvasWidth / width})`;
}
}
if (textDivProperties.angle !== 0) {
transform = `rotate(${textDivProperties.angle}deg) ${transform}`;
}
if (transform.length > 0) {
textDiv.style.transform = transform;
}
if (textDivProperties.hasText) {
this._container.append(textDiv);
}
if (textDivProperties.hasEOL) {
const br = document.createElement("br");
br.setAttribute("role", "presentation");
this._container.append(br);
}
}
_render(timeout = 0) {
const capability = (0, _util.createPromiseCapability)();
let styleCache = Object.create(null);
const canvas = this._document.createElement("canvas");
canvas.height = canvas.width = DEFAULT_FONT_SIZE;
this._layoutTextCtx = canvas.getContext("2d", {
alpha: false
});
if (this._textContent) {
const textItems = this._textContent.items;
const textStyles = this._textContent.styles;
this._processItems(textItems, textStyles);
capability.resolve();
} else if (this._textContentStream) {
const pump = () => {
this._reader.read().then(({
value,
done
}) => {
if (done) {
capability.resolve();
return;
}
Object.assign(styleCache, value.styles);
this._processItems(value.items, styleCache);
pump();
}, capability.reject);
};
this._reader = this._textContentStream.getReader();
pump();
} else {
throw new Error('Neither "textContent" nor "textContentStream" parameters specified.');
}
capability.promise.then(() => {
styleCache = null;
if (!timeout) {
render(this);
} else {
(0, _display_utils.deprecated)("The TextLayerRender `timeout` parameter will be removed in the " + "future, since streaming of textContent has made it obsolete.");
this._renderTimer = setTimeout(() => {
render(this);
this._renderTimer = null;
}, timeout);
}
}, this._capability.reject);
}
}
exports.TextLayerRenderTask = TextLayerRenderTask;
function renderTextLayer(renderParameters) {
const task = new TextLayerRenderTask({
textContent: renderParameters.textContent,
textContentStream: renderParameters.textContentStream,
container: renderParameters.container,
viewport: renderParameters.viewport,
textDivs: renderParameters.textDivs,
textContentItemsStr: renderParameters.textContentItemsStr
});
task._render(renderParameters.timeout);
return task;
}